.\"	$OpenBSD: cgthree.4,v 1.22 2012/08/18 08:44:25 jmc Exp $
.\"
.\" Copyright (c) 2001 Jason L. Wright (jason@thought.net)
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.Dd $Mdocdate: August 18 2012 $
.Dt CGTHREE 4 sparc64
.Os
.Sh NAME
.Nm cgthree
.Nd 8-bit color frame buffer
.Sh SYNOPSIS
.Cd "cgthree* at sbus?"
.Cd "wsdisplay* at cgthree?"
.Sh DESCRIPTION
The
.Nm
is an SBus color frame buffer.
.Pp
The
.Nm
driver interfaces the frame buffer with the
.Xr wscons 4
console framework.
It does not provide direct device driver entry points
but makes its functions available via the internal
.Xr wsdisplay 4
interface.
.Sh DISPLAY RESOLUTION
If the
.Nm
frame buffer is used as the console display, it is possible, for some models,
to select a different resolution than the default 1152x900 or 1024x768
by changing the OpenPROM environment.
To change the default resolution, type the following:
.Pp
.Em \   ok
setenv
.Em output-device
screen:r1152x900x66
.Pp
to change to a 66Hz 1152x900 resolution.
.Pp
If the
.Nm
frame buffer is a secondary display, or a serial console is used, the
display resolution can not be changed without using an
.Em nvramrc
OpenPROM script.
Refer to the
.Em Sun Frame Buffer FAQ
for details.
.Pp
The
.Nm
frame buffer accepts the following resolutions:
.Pp
.Bl -tag -width screen:r1280x1024x76 -compact
.It screen:r1024x768x77
Super VGA 1024x768, with a refresh rate of 77Hz.
This is the default setting on model 501-2691.
.It screen:r1152x900x66
Standard 1152x900, with a refresh rate of 66Hz.
This is the default setting on older models (501-1415 and 501-8044).
.It screen:r1152x900x76
Standard 1152x900, with a refresh rate of 76Hz.
This is the default setting on more recent models (501-1718 and 501-1909).
.El
.Pp
Note that not all models support settings other than their default setting.
.Sh SEE ALSO
.Xr intro 4 ,
.Xr sbus 4 ,
.Xr wscons 4 ,
.Xr wsdisplay 4
.Rs
.%T Sun Frame Buffer FAQ
.%U http://www.sunhelp.org/faq/FrameBuffer.html
.Re
